The brace brought Bale up to 18 goals in all competitions this season, and to 15 in La Liga, though it is in continental play where he has often struggled in 2017-18.
Bale has largely been consigned to a place on the bench during the knockout stages of the Champions League this season but, with injury problems seemingly behind him, the 28-year-old has found form with Madrid's Kiev showdown against Liverpool only two weeks away.
He fired a Camp Nou equaliser in El Clasico last weekend and, speaking to reporters after the Celta rout, Zidane said: "I don't know my team yet [for the final] but it's better to have everyone plugged in.
"Then, of course, it will be a headache to select the team for the final.
"We had a great game and that was important. We were very professional, scoring six goals and playing a lot of football. We did very well."
On Bale's showing, the France great added: "He is very good, he has shown that. He was good at everything tonight.
"I am happy for him. But the important thing is that we all arrive in optimal form."